1. Field of the Invention
The present invention relates to color-change materials. More particularly, this invention relates to color-change materials whose appearances change from their ordinary ones upon application of heat and/or a medium such as water.
2. Description of the Related Art
Thermochromic articles obtained by processing reversibly thermochromic materials have conventionally been used extensively in the fields of toys, ornaments, etc. On the other hand, converted papers are known which have a porous layer containing a low-refractive-index pigment and which, upon liquid absorption, becomes transparent and develops a colored image not seen in their ordinary state (see, for example, Unexamined Japanese Patent Publication No. Sho. 50-5097).